Thermal Isolation Disc for Silencer

ABSTRACT

A thermal isolation disc for an exhaust silencer includes a first ring configured for attachment to an exhaust pipe defining a center axis, a second ring configured for attachment to a composite outer housing of a silencer, and a gasket sandwiched between the first and second rings.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser.No. 61/750,908, filed Jan. 10, 2013.

TECHNICAL FIELD

This invention generally relates to a thermal isolation disc for asilencer as used in an exhaust system.

BACKGROUND

Exhaust systems often include mufflers or silencers to reduceundesirable noise generated by the exhaust system. Silencers typicallyinclude an outer housing through which an exhaust pipe extends from aninlet to an outlet. Acoustic material, such as fiberglass for example,can surround the exhaust pipe and fill an interior cavity of the outerhousing to provide desired noise reduction. Optionally, the exhaust pipecan be formed to include perforations in fluid communication with theinterior cavity of the outer housing to provide the desired noisereduction.

The exhaust pipes are subjected to high exhaust gas temperatures. Inorder to provide a weight savings, the outer housing of the silencerscan be made from composite materials; however, under certain operatingconditions the exhaust gas temperatures may exceed the meltingtemperature of the composite outer housing. One proposed solution hasbeen to use a thermal isolation disc at the connection interface betweenthe outer housing and the exhaust pipe. Current thermal isolation discsuse distance from the heat source to keep the temperature at theinterface between the composite material and steel material of theexhaust pipe below the material limits of the composite material. Thisis done by increasing an outer diameter of the disc until the distancebetween an inner diameter and the outer diameter is sufficient such thatheat at the outer diameter is below the composite material limit.Optionally, an axially extending, cone-shaped disc has been used toconnect the exhaust pipe to the outer housing. Both of theseconfiguration are disadvantageous due to the need for larger areas orlengths to accommodate the enlarged diameter or the length of the cone.

SUMMARY

In one exemplary embodiment, a thermal isolation disc for an exhaustsilencer includes a first ring configured for attachment to an exhaustpipe defining a center axis, a second ring configured for attachment toa composite outer housing of a silencer, an a gasket sandwiched betweenthe first and second rings.

In a further embodiment of the above, the first and/or second rings arecomprised of steel.

In a further embodiment of any of the above, the gasket is comprised ofan insulating material.

In a further embodiment of any of the above, the disc includes a thermalisolation ring mounted to an outer periphery of the second ring.

In a further embodiment of any of the above, the first and second ringsare axially separated from each other by the gasket.

In a further embodiment of any of the above, portions of the first andsecond discs overlap each other in a radial direction.

In a further embodiment of any of the above, an inner peripheral edge ofthe second ring is radially separated from an outer peripheral edge ofthe first ring by the gasket.

In another exemplary embodiment, a silencer for an exhaust systemincludes an outer housing comprised of a composite material, an exhaustpipe mounted to the outer housing at an attachment interface, theexhaust pipe defining a center axis, and a thermal isolation discpositioned between the outer housing and exhaust pipe at the attachmentinterface. The thermal isolation disc includes a first ring attached tothe exhaust pipe, a second ring attached to the outer housing, and agasket sandwiched between the first and second rings.

In a further embodiment of any of the above, the thermal isolation discincludes at least one fastener that secures the first ring, second ring,and gasket together.

The foregoing features and elements may be combined in any combinationwithout exclusivity, unless expressly indicated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a vehicle exhaust system incorporating thesubject invention.

FIG. 2 is a second view of a thermal isolation disc used to connect apipe to an exhaust component.

FIG. 3 is an end view of the thermal isolation disc of FIG. 2.

FIG. 4 is a schematic view of another example of a thermal isolationdisc.

DETAILED DESCRIPTION

FIG. 1 shows an exhaust system 10 with an internal combustion engine 12that generates exhaust gases that are transmitted downstream to one ormore exhaust components, such as a muffler or silencer 14. The silencer14 is comprised of an outer housing 16 defining an interior cavity 18(FIG. 2) and which includes an inlet 20 and an outlet 22.

As shown in FIG. 2, at least one exhaust pipe 24 is associated with thesilencer 14. The exhaust pipe 24 defines a central axis A and can becomprised of a single pipe that extends from the inlet 20 to the outlet24, or the exhaust pipe 24 can be comprised of multiple pieces connectedto each other with at least one piece being associated with the outletand another piece being associated with the inlet. The exhaust pipe 24is mounted to the outer housing 16 at an attachment interface 30. Athermal isolation disc 32 is positioned between the outer housing 16 andthe exhaust pipe 24 at the attachment interface 30. In one example, theattachment interface 30 is located at the inlet 20 and outlet 22 of theouter housing 16; however, the thermal isolation disc 32 may only beused at one of the inlet 20 or outlet 22 as needed.

The outer housing 16 of the muffler 14 is comprised of a compositematerial that includes a resin material with reinforcing fibers. Anytype of resin material and any type of fiber material can be used aslong as the materials are sufficient to meet the specified temperaturelevels for the exhaust system 10. Using a composite material for themuffler 14 provides a significant overall weight reduction for theexhaust system 10.

In one example, the exhaust pipe 24 is comprised of a steel material.The exhaust pipe 24 can be attached to the thermal isolation disc 32using any of various attachment methods such as welding, brazing,adhesive, fasteners, clamps, etc.

The thermal isolation disc 32 provides a reduction in heat transfer fromthe exhaust pipe, which is subjected to high temperature exhaust gases,to the outer housing 16, which is made from the composite materialhaving a melting temperature that is less than that of the exhaust pipe24. The thermal isolation disc 32 is comprised of a first disc or ring40 that is attached to the exhaust pipe 24, a second disc or ring 42that is attached to the outer housing 16, and a gasket 44 that issandwiched between the first 40 and second 42 rings. The sandwichcreates a thermal discontinuity which keeps the majority of theconduction energy passing through the thermal isolation disc 32 andlowering the temperature at an outer peripheral edge of the disc.

In one example, the first 40 and second 42 rings are comprised of asteel material and the gasket 44 is comprised of an insulating material.The first ring 40 can be fixed to the exhaust pipe 24 by any of variousattachment methods including welding, brazing, clamps, etc.

In one example, one or more fasteners 50 are used to secure the firstring 40, second ring 42, and gasket 44 together. The fasteners 50 can bebolts, rivets, screws, or some form of metal displacement joint, forexample. The fasteners 50 compress the gasket 44 between the rings 40,42.

In one example, a thermal isolation ring 60 is mounted to an outerperipheral edge 62 of the second ring 44. The thermal isolation ring 60fits in a groove 64 that is formed in the outer housing 16. The housing16 includes radially inwardly extending portions 66 that face each otherand which are separated from each other by a gap 68 that defines theinlet 20 as shown in FIG. 2. The groove 64 is formed in a distal endface of the radially inwardly extending portions 66. The thermalisolation ring 60 is pressed into the groove 64 and surrounds the inletopening. In one example, the thermal isolation ring 60 is comprised of asilicon material.

In the example shown, the outer peripheral edge 62 of the second ring 42is pressed into an inner peripheral surface of the thermal isolationring 60. The second ring 42 can then be further secured to the housing16 if needed by any of various attachment methods such as adhesive, forexample.

In the embodiment shown in FIGS. 2-3, the first 40 and second 42 ringsare axially separated from each other by the gasket 44. As such,portions 70, 72 respectively of the first 40 and second 42 discs overlapeach other in a radial direction. In other words, the outer peripheralportion 70 of the inner ring 40 overlaps the inner peripheral portion 72of the outer ring 42. These portions 70, 72 also face each other in anaxial direction, but are separated from each other by the gasket 44.

In the example of FIG. 4, a thermal isolation disc 32′ uses concentricsurfaces of the rings 40′, 42′ to capture the gasket 44′ between them.As such, an inner peripheral edge 80 of the second ring 42′ is radiallyseparated from an outer peripheral edge 82 of the first ring 40′ by thegasket 44′. The gasket 44′ can be further secured to the rings 40′, 42′if needed by any of various attachment methods such as adhesive, forexample. The first or inner ring 40′ can be fixed to the exhaust pipe 24by any of various attachment methods such as welding, brazing, etc. Thesecond ring 42′ can then be further secured to the housing 16 if neededby any of various attachment methods such as adhesive, for example.

The use of a composite housing in combination with a thermal isolationdisc to mount the inlet and outlet pipes provides a compact andlightweight exhaust component. The composite material significantlyreduces weight as compared to prior steel housing configurations.Further, the subject thermal isolation disc allows the use of thecomposite material housing without significantly increasing the overallsize of the connection interfaces for the inlet and outlet pipes, i.e.the packaging space is not adversely affected.

Although an embodiment of this invention has been disclosed, a worker ofordinary skill in this art would recognize that certain modificationswould come within the scope of this invention. For that reason, thefollowing claims should be studied to determine the true scope andcontent of this invention.

1. A thermal isolation disc for an exhaust silencer comprising: a firstring configured for attachment to an exhaust pipe defining a centeraxis; a second ring configured for attachment to a composite outerhousing of a silencer; and a gasket sandwiched between the first andsecond rings.
 2. The thermal isolation disc according to claim 1 whereinthe first ring is comprised of steel.
 3. The thermal isolation discaccording to claim 1 wherein the second ring is comprised of steel. 4.The thermal isolation disc according to claim 1 wherein the first andsecond rings are comprised of steel.
 5. The thermal isolation discaccording to claim 4 wherein the gasket is comprised of an insulatingmaterial.
 6. The thermal isolation disc according to claim 1 wherein thegasket is comprised of an insulating material.
 7. The thermal isolationdisc according to claim 1 including at least one fastener that securesthe first ring, second ring, and gasket together.
 8. The thermalisolation disc according to claim 1 including a thermal isolation ringmounted to an outer periphery of the second ring.
 9. The thermalisolation disc according to claim 1 wherein the first and second ringsare axially separated from each other by the gasket.
 10. The thermalisolation disc according to claim 1 wherein portions of the first andsecond discs overlap each other in a radial direction and are axiallyseparated from each other by the gasket.
 11. The thermal isolation discaccording to claim 1 wherein an inner peripheral edge of the second ringis radially separated from an outer peripheral edge of the first ring bythe gasket.
 12. A silencer for an exhaust system comprising: an outerhousing comprised of a composite material; an exhaust pipe mounted tothe outer housing at an attachment interface, the exhaust pipe defininga center axis; and a thermal isolation disc positioned between the outerhousing and exhaust pipe at the attachment interface, the thermalisolation disc comprising a first ring attached to the exhaust pipe, asecond ring attached to the outer housing, and a gasket sandwichedbetween the first and second rings.
 13. The silencer according to claim12 wherein the gasket is comprised of an insulating material and thefirst and second rings are comprised of a steel material.
 14. Thesilencer according to claim 12 wherein the first and second rings areaxially separated from each other by the gasket.
 15. The silenceraccording to claim 12 wherein an inner peripheral edge of the secondring is radially separated from an outer peripheral edge of the firstring by the gasket.
 16. The silencer according to claim 12 wherein thefirst ring is comprised of steel.
 17. The silencer according to claim 12wherein the second ring is comprised of steel.
 18. The silenceraccording to claim 12 wherein the first and second rings are comprisedof steel.
 19. The silencer according to claim 12 wherein the gasket iscomprised of an insulating material.
 20. The silencer according to claim12 wherein the thermal isolation disc includes at least one fastenerthat secures the first ring, second ring, and gasket together.